Delaware prison administrators dismissed warnings of trouble brewing at the state's maximum-security prison in the days leading up to a deadly inmate uprising and hostage-taking, independent investigators said in a report released Friday.

The dismissal of the security warnings at James T. Vaughn Correctional Center in Smyrna was indicative of an overcrowded, understaffed facility plagued by mismanagement, a lack of communication, a culture of negativity, and adversarial relationships among prison staff, administrators and inmates, according to the independent review ordered by Gov. John Carney.

Carney ordered the review after inmates seized a building at the prison in February and took several prison workers hostage, setting off a standoff lasting nearly 20 hours.

Correctional officer Steven Floyd was killed before authorities used a backhoe to breach a wall and rescue a female counselor. Two other guards also taken hostage had been released earlier after being tormented and beaten by inmates.

According to the independent review, the February uprising in Building C was preceded by an incident two weeks earlier in which some inmates in that same building refused to return to their cells after recreation time - until they were allowed to speak with a supervisor about housing conditions. After that incident, some correctional officers - including Floyd - told supervisors that the instigators should be moved to another building for security reasons. The request was dismissed by higher-ranking officials.

"Lack of action following a potential inmate protest in the C-Building on January 15, 2017, did little to discourage a subset of inmates from acting out again," investigators said.

Investigators said the February uprising could have occurred elsewhere at the Vaughn prison, but the unique circumstances in Building C, which housed a volatile mix of inmates moving down from maximum to medium security, and inmates moving up from medium to maximum security, "hastened the inevitable."

A criminal investigation into the uprising and Floyd's death is continuing. Authorities said in early August that they hope to present an indictment for consideration by a New Castle County grand jury within 90 days. Officials conducting the independent review noted that they did not have access to police investigative reports, Department of Correction internal affairs documents, or other reports involved in the criminal investigation.

"This much is clear: we have systemic issues within our correctional system that must be addressed, and we are committed to addressing them," Carney said in a statement Friday. "We've already made progress, but there is more work ahead of us."

Officials conducting the independent review have proposed several recommendations, including reducing mandatory overtime for prison guards, improving communications and training at all levels of the corrections department and ensuring that prison staff understand and consistently follow policies and procedures.

Inmates, meanwhile, deserve consistent and humane treatment, with a focus on rehabilitation instead of punishment and access to programs and counseling aimed at preventing them from becoming repeat offenders, officials said.

"For years, excessive mandated overtime and fatigue; the inconsistent application of policies and procedures; inconsistent management; and the lack of communication, adversarial relationships, and a general lack of respect at all levels of the JTVCC have contributed to poor correctional officer morale and increasing hostility between inmates and correctional officers," the reviewers concluded.

"At the same time, the lack of inmate programming and training and the inconsistent application of policies has worsened inmate morale, and left them with extensive amounts of idle time in which to plan disruptive, dangerous, and deadly acts."